On 08/24/2010 04:35 PM, Anthony Liguori wrote:
It's about metadata writes. If an operation changes metadata, we
must sync it to disk before writing any data or other metadata which
depends on it, regardless of any promises to the guest.
Why? If the metadata isn't sync, we loose the write.
But that can happen anyway because we're not sync'ing the data
We need to sync the metadata in the event of a guest initiated flush,
but we shouldn't need to for a normal write.
1. Allocate a cluster (increase refcount table)
2. Link cluster to L2 table
3. Second operation makes it to disk; first still in pagecache
4. Crash
5. Dangling pointer from L2 to freed cluster
--
error compiling committee.c: too many arguments to function
